First of all, high school should study hard. It is difficult to get into a good university without hard work. You should have your own study plan and be efficient. The hard work mentioned here is not always learning, no one is a saint, and it is impossible to be energetic forever. Therefore, we should try our best to concentrate on ourselves, learn some courses that use more brains when we are energetic, and choose some memories or copied contents to boost our spirits when our brains are confused. It is necessary to combine work and rest, go to bed early and get up early, and have a good sleep before starting the next day's study.
If you want to make your English level stand out, I suggest you develop your oral English besides memorizing words, because Beijing Foreign Studies University requires not only English teachers' ability, but also practical ability. When eating, you can watch some English movies, listen to some English songs and learn their standard pronunciation, which is also very helpful for listening.
Of course, if your English ability in a single subject is outstanding enough and other cultural courses are not ideal, you can also apply for independent enrollment in Beijing Foreign Studies University. This difficulty is definitely greater than the college entrance examination. It's about your comprehensive English ability, not just your test ability, so you should also be mentally prepared. You think you are strong enough, but in big cities such as Beijing and Shanghai, there may be people who are stronger than you competing with you. You must not take it lightly.
In short, if you want to go to Beijing Foreign Studies University, you must first lay a good foundation in English, and then go to college to further improve your English.